The present invention relates to a hub odometer designed to measure a distance traveled by a trailer, an industrial vehicle or the like. More: particularly, the invention relates to a hub odometer capable of not only measuring a traveling distance accurately irrespective of a rotational direction of a vehicle wheel but also facilitating data management thereof.
In the case of a trailer, an industrial vehicle or the like, an odometer is attached to an axle and, in this axle portion, measuring is independently performed for a traveling distance. The attachment of such a hub odometer enables a distance traveled by a car body to be measured for example even when a car body of the trailer is detached from a driver""s seat.
Heretofore, The hub odometer has been provided with a mechanism for mechanically measuring the number of revolutions by utilizing a gear or the like, thereby has displayed a traveling distance directly. However, in such a mechanical odometer, it is necessary to go to the axle area to visually read a traveling distance, and reading is difficult if the odometer is soiled. Therefore, there was a problem of complicated data management regarding traveling distances. In addition, in the mechanical odometer, a traveling distance is reduced when a rotational direction of the vehicle wheel is reversed against forward rotation. Thus, there was a problem of impossibility of measuring traveling distances accurately, especially in the case of the industrial vehicle frequently moved back and forth.
Furthermore, in U.S. Pat. No. 4,697,278, an electronic hub odometer was disclosed, which measures the number of revolutions by a magnetic reed switch, and transmits data of the measured result to a remote unit by flashing an infrared light emitting diode. However, if the odometer is soiled, it is difficult for the remote unit to detect the flashing of the light emitting diode. Thus, data management was neither accurate nor easy.
It is an object of the present invention to provide a hub odometer capable of accurately measuring a traveling distance irrespective of a rotational direction of a vehicle wheel, and facilitating data management thereof.
In order to achieve the foregoing object, a hub odometer of the present invention comprises: an eccentric weight rotably supported in a center axis position of an axle hub; a case attached to the axle hub to surround the eccentric weight; a non-contact measuring mechanism disposed to measure the number of revolutions in a relative relation to the case and the eccentric weight; and a transponder including a memory for storing measuring data of the measuring mechanism, a transmitting circuit for transmitting the data stored in the memory, and a receiver for receiving an interrogation wave from a remote unit, the transmitting circuit being actuated on the basis of the interrogation wave.
As described above, the non-contact measuring mechanism is used for measuring the number of revolutions of the axle hub, which becomes a reference for calculating a traveling distance. Accordingly, a traveling distance can be accurately measured irrespective of a rotational direction of a vehicle wheel. In addition, the transponder is provided to transmit measuring data of the measuring mechanism on the basis of an, interrogation wave from the remote unit. Accordingly, the measuring data can be displayed on an optional data management unit or the like, and the necessity of visually reading a traveling distance for each axle can be eliminated. Thus, data management can be facilitated.
The non-contact measuring mechanism can be composed of one of the following combinations: a magnet and a magnetic pickup coil; a projecting source, an optical sensor and a light shielding plate; the projecting source, the optical sensor and a reflector; a proximity sensor for detecting a change in a resonance frequency of a high-frequency magnetic field and a metallic piece for detection.
A single or a plurality of the measuring mechanisms may be provided. Especially, by shifting measuring positions of the plurality of measuring mechanisms from each other in a hub circumferential direction, a rotational direction of the vehicle wheel can be specified on the basis of measuring data thereof. Thus, data management correlating the rotational direction with a traveling direction can be performed.